The Polarographic Observations on Percarbonic Acids and Percarbonates.

Polarization curves for the electrolytic reduction of oxygen are determined for several metals by application of a polarographie method previously described (1). The contributions of the two and four electron processes, i.e., reduction of oxygen to hydrogen peroxide and to water, respectively, are determined. The electrolytic reduction of oxygen on chromium, tantalum, titanium, and tungsten may yield appreciable quantities of hydrogen peroxide. Very little hydrogen peroxide is formed on zirconium and molybdenum.

Section: Zirco~zium and Molybdenumsupporting

confidence: 64%

A Polarographic Method for the Indirect Determination of Polarization Curves for Oxygen Reduction on Various Metals

Delahay

Stagg

1952

“…In a recent paper Hoxeng and Prutton (9) present an interesting discussion of their observations on the corrosion of zinc, particularly in presence of bicarbonates, and make use of an explanation advanced by two of the present authors (10,11) concerning the acceleration of zinc corrosion through cathodic depolarization due to percarbonic acid formed between CO"-and hydrogen peroxide which is known to be formed during the corrosion of zinc.…”

Section: A Homogeneous Reactions Witho~d Oxidationmentioning

confidence: 96%

Potential-pH Diagram of Zinc and its Applications to the Study of Zinc Corrosion

Delahay¹,

Pourbaix²,

Rysselberghe³

1951

“…A small amount of oxygen on the zinc oxide can be reduced into H 2 O 2 . 55 Rysselberghe et al 66 found that H 2 O 2 can react with carbonic acid to form percarbonic acid. As a result, reduction of oxygen in the four-electron process is easier in the presence of a small amount of carbonic acid than in the case without carbonic acid, as verified by Ref.…”

Section: Resultsmentioning

confidence: 99%

Effect of Relative Humidity on the Initial Atmospheric Corrosion Behavior of Zinc during Drying

Cheng

Song

et al. 2013

The effects of relative humidity on the initial atmospheric corrosion of zinc during drying of chloride-contained absorbed thin electrolyte layer was investigated by mass loss, scanning electron microscopy (SEM), cathodic polarization curves, pre-Tafel polarization curves fitting method and electrochemical impedance spectroscopy (EIS). The results showed that the zinc corrosion rate decreased with increasing relative humidity in the first 2 h. After 72 h of exposure, the corrosion rates of zinc were ranked as: 75% RH < 85% RH < 97% RH. And the morphology of corrosion products at 75% RH appeared more compact than that of 85% and 97% RH.Zinc is widely exposed to the atmosphere, particularly in the form of steel coatings and paint pigments designed to protect underlying metal against corrosion by the sacrificial loss of zinc because of its relatively lower corrosion potential (E corr ) in the electrochemical series. Substantial research on the corrosion of zinc materials has been performed in field exposure and controlled laboratory environments. [1][2][3][4][5] Indeed, the importance of zinc is enhanced especially in coastal regions, where airborne salinity more significantly affects the degradation of structures than pollution with reduced industrial pollutants. 6 Deposition of airborne salinity on metal components can cause them damage and reduce their service life.Chloride deposition is a major contributor to increased atmospheric corrosivity in marine environments. 7 Oceans provide a source of chlorine in the form of marine salt (e.g., NaCl and MgCl 2 ), which can be directly emitted by the ocean or formed by turbulent ocean states and surf action and transported inland predominantly by coastal wind patterns. 2 Atmospheric corrosion can be accelerated by the deposition of marine salts. Lindström et al. 3 reported that the zinc mass loss of samples covered with sodium chloride particles remains constant in the presence of CO 2 regardless of temperature; by contrast, the strong temperature dependence of metal loss on CO 2 -free air was observed. This study showed that CO 2 is important for zinc corrosion. In fact, sodium chloride is the main stimulator of atmospheric corrosion in metals, and a substantial amount of research on this type of corrosion has been done. 2,4,6 Sodium chloride is hygroscopic; thus, atmospheric moisture may condense and form droplets and/or adsorbed thin electrolyte layers (ATELs) containing chloride ions when the temperature drops and relative humidity (RH) rises. By contrast, increases in temperature and/or drops in RH lead to the evaporation of sodium chloride electrolyte (drying) and increase in chloride concentration in the ATELs. 8 The diameter and thickness of droplets and/or thickness of ATELs also change with variations in the ambient temperature and RH.Atmospheric corrosion under droplets has been extensively studied. 1,[9][10][11][12] In general, when droplets on a metal surface evaporate, they form thin electrolytic films and drastically increase the metal corrosion rate. Sinc...